Machines for straightening bars or tubes



Oct. 13, 1970 w. E. ALDRED 3,533,257

MACHINES FOR STRAIGHTENING BARS 0R TUBES Filed June 6, 1968 5 Sheets-Sheet 1 g ELIQ m H M WMZZ MW Oct. 13, 1970 w. E. ALDRED MACHINES FOR STRAIGHTENING BARS 0R TUBES Filed June a, 1968 5 Sheets-Sheet 2 s L k K Wadi/KM W W /mxzm Oct. 13, 1970 w. E. ALDRED 3,533,257

MACHINES FOR STRAIGHTENING BARS OR TUBES Filed June 6, 1968 5 Sheets-Sheet 5 Oct. 13, 1970 w. E. ALDRED MACHINES FOR STRAIGHTENING BARS OR TUBES 5 Sheets-Sheet 4.

Filed June 6, 1968 IZ/ /Al US. CI. 72-99 11 Claims ABSTRACT OF THE DISCLOSURE A straightening machine for bars or tubes comprises at least three pairs of driven straightening rolls arranged in line along the path of the bar or tube to be straightened, and means for offsetting the centre pair of rolls from the outer pairs of rolls, one of the rolls of each pair being urged towards the other roll of the pair by an hydraulic jack, the hydraulic pressure of which jack is capable of being set by a pressure relief valve associated with the jack whereby any excess loading will cause the relief valve to lift and will hence prevent an increase of the predetermined hydraulic pressure on the bar or tube being straightened.

This invention relates to machines for straightening bars or tubes.

According to the invention a straightening machine for bars or tubes comprises at least three pairs of driven straightening rolls arranged in line along the path of the bar or tube to be straightened, means for raising and lowering one of the rolls of each pair relatively to the other roll, means for raising and lowering the centre pair of rolls, in unison, into and out of the path of the bar or tube to be straightened to offset the centre pair of rolls from the outer pairs of rolls and means for arranging the rolls of each pair of rolls so that the bar or tube is rotated as it passes longitudinally therebetween, characterised in that one of the rolls of each pair is urged towards the other roll of the pair by a hydraulic jack, the hydraulic pressure of which jack is capable of being set by a pressure relief valve associated with the jack whereby any excess loading will cause the relief valve to lift and will hence prevent an increase of the predetermined hydraulic pressure on the bar or tube being straightened. It is found that this method of urging the rolls of each pair towards each other and hence into contact with the bar or tube being straightened, prevents damage to the tube or the machine by excess loading.

Preferably for each pair of rolls there is an hydraulic jack for urging the upper roll towards the associated lower roll. It is also preferred that each said hydraulic jack is provided with a high load cylinder and a low load cylinder one of which may be selected for the application of hydraulic pressure on the bar or tube being straightened and both of which are provided with their separate pressure relief valves. It is further preferred that, in the case of the centre pair of rolls, a second hydraulic jack is provided for moving the lower roll vertically out of alignment with the lower rolls of the outer pairs of rolls, the centre lower roll being linked to its respective upper roll whereby the said second hydraulic jack moves the linked rolls in unison so that the gap therebetween is maintained constant.

A further feature of the invention is that the deflection of the path of the bar or tube being straightened which is effected by offsetting the centre pair of rolls from the outer pair of rolls, is applied prior to the passage of a bar or tube between the rollers, or during the passage of 3,533,257 Patented Got. 13, 1970 a bar or tube between the rolls and subsequently to the leading end of the bar or tube passing through the centre pair of rolls.

Adjustable mechanical stops are preferably provided for limiting the movement of each vertically movable roll towards its associated roll, which stops are preferably provided by the means for raising and lowering the respective roll.

By way of example, a specific embodiment constructed in accordance with the invention will now be described with reference to the accompanying drawings in which:

FIG. 1 is an elevation of a tube straightening machine;

FIG. 2 is a sectional elevation of one of the outer top straightening rolls of the machine shown in FIG. 1;

FIG. 3 is an elevation of the centre pair of straightening rolls of the machine shown in FIG. 1;

FIG. 4 is a sectional elevation of the hydraulic means for operating the bottom straightening roll shown in FIG. 3; and

FIG. 5 is a diagram of the hydraulic circuit of the machine shown in FIG. 1.

With reference to FIG. 1, the tube straightening machine comprises three pairs of opposed straightening rolls 10, 11; 12, 13; 14, 15 located one pair after the other along the path of the tube 9 being straightened. The top three rolls 10, 12, 14 are driven by an electric motor 16, whilst the bottom three rolls 11, 1.3, 15 are driven by another electric motor 19. The machine is also provided with a pair of pinch rolls 17, 18 to pass the tubes being straightened into the first pair of straightening rolls 10, 11. These pinch rolls are driven by an electric motor 20.

Each roll 10 to 15 and 17, 18 is a paraboloid and is adjusted angularly to the path of the tube being straightened so that the tube is rotated as it is passed between the rolls and so that there is the maximum surface contact between the rolls and between the tube being straightened. Each of the bottom rolls .11, 15, 18 is fixed in height but the position of each of the other rolls, including the bottom roll 13, is adjustable vertically by means described below. The spacing between each pair of rolls may thus be adjusted to suit different diameters of tube, and is recorded on the associated dial 8. The centre pair of straightened rolls 12, 13 may also be moved vertically, in unison, to effect a deflection of the path of the tube being straightened. As described below, this deflection may be applied either before or after the tube is passed between these rolls 12, 13.

Mechanical stops are provided, in the manner described below, to locate the required position of each roll, and each roll is maintained against its particular stop by an hydraulic jack. Adjustment of the positions of these mechanical stops can take place either before or during the passage of a length of tube between the pairs of rolls.

At either end of the machine there is provided a driven conveyor 22, 23 for conveying each tube of a bundle of tubes, in succession, to the pinch rolls 17, 18 and for conveying the straightened tubes away from the machine respectively.

Sonic beam devices (not shown) are provided after or downstream of the pinch rolls and after or downstream of the last pair of straightening rolls, the purpose of which is described below.

The general means of operation of the machine shown in FIG. 1 will now be described. The spacing between the three pairs of straightening rolls and the angular relationship of the rolls of the path of the tubes to be straightened are set to suit the particular diameter of the tubes. The conveyor at the leading end of the machine is operated to drive one of the tubes between the pinch rolls 17, 18. The first-mentioned sonic beam is then blocked to close the top pinch roll onto the tube. The pinch rolls then drive the tube through a bell-shaped guide 21 and Oct. 13, 1970 w. E. ALDRED MACHINES FOR STRAIGHTENING BARS OR TUBES 5 Sheets-Sheet 5 Filed June 6, 1968 by an electric motor 59 by means of a worm 60 fixed to the nut, a wormwheel 61 in engagement with the worm and a drive shaft 62 connecting the shaft of the electric motor to the wormwheel. The piston rod 54 may thus be raised and lowered in like manner to the piston rods associated with the upper straightening rolls.

In the case of the bottom centre straightening roll 13, the contacting surfaces which comprise its mechanical stop are the underside of the piston 55 and the top side of the base plate 53 of the cylinder 52. These surfaces are maintained in contact during normal working by the introduction of oil at a pre-set pressure into the cylinder above the piston 55. However, if excess pressure is ap plied to the roll 13 by e.g. an oversize tube, an asso ciated relief valve (see FIG. 5) is opened to allow a quantity of oil to flow out of the cylinder 52 to tank and hence to allow the said contacting surfaces to separate. The load in the cylinder 52 is thus maintained constant.

As described above, the centre straightening rolls 12, 13 are vertically movable in unison to offset the rolls from the outer pairs of straightening rolls and hence to apply a deflection to the path of the tube being straightened. The means provided for this purpose comprise a parallel linkage mechanism comprising levers 70, 71 pivotally mounted about horizontal spindles 72, 73 respectively. One end of lever 70 is fixed to the wormwheel 41 associated with the upper centre roll 12 and one end of lever 71 is fixed to the wormwheel 61 associated with the lower centre roll 13, the other ends of the levers being pivotally connected by a link 74. Thus vertical movement of the lower centre roll by the introduction of oil into the cylinder 52 will automatically raise the upper centre roll by an equivalent amount.

The hydraulic circuit for operation of the above described high load and low load cylinders and the associated relief valves will now be described. With reference to FIG. 5, the cylinders provided for each of the movable rolls are shown diagrammatically and are given the same reference numerals as used above.

Three pumps P1, P2, P3 are provided to feed oil to the high and low load cylinders at the required pressures. Pump P1 which is capable of feeding oil at high pressure (e.g. 4480 lb./ sq. in.) to the cylinders of the straightening rolls 10, 12, 13, 14 is mechanically coupled to pump P2 which is capable of feeding oil at low pressure (eg 1000 lb./sq. in.) to the annulus 48 below the piston 46 of each of the low load cylinders 47. Oil is continually fed to each annulus 48 during periods of operation to ensure that the pistons 46 remain lifted. The pumps P1, P2 are driven by an electric motor E1.

The third pump P3 is capable of feeding oil at high pressure to the cylinder 66 of the upper pinch roll 17 and also to the cylinder 52 associated with the lower centre straightening roll 13. This pump P3 is separately driven by an electric motor E2. The cylinder 52 of the lower centre straightening roll 13 is thus fed with oil by both pumps P1, P3.

A three-way valve V1 controlled by a selector switch enables the operator to use either the high load or the low load cylinders, the selection being in accordance with the tube diameter and thickness, and with the material tensile stress. These parameters, together with the tube condition, enable the operator to select the most desirable load. This valve V1 is solenoid pilot operated, a pilot pressure being applied through a reducer valve V8.

Accumulators A1, A2A are provided in the circuits for the high load and low load cylinders respectively to allow for oil fluctuations. A further accumulator A2B is provided in the circuit for the cylinder 52 of the lower centre straightening roll, the accumulator being connected into its circuit via a speed control valve VC which controls the speed of flow of oil into the circuit by a needle valve and permits free flow into the accumulator.

The circuit for the low load cylinders is safe-guarded by a general relief valve V16A set at a high pressure in the case of very large overloads, or by a control valve V12A in conjunction with a speed control valve V10A in the case of normal overloads. This speed control valve V10A has a free flow towards the low load cylinders but a needle valve to control the speed of any flow of oil from the cylinders. Similarly, the circuit for the high load cylinders is protected by a general relief valve V16B set at high pressure or by a control valve V12B in conjunction with a speed control valve V10B. The function of these speed control valves V10A, V10B is to prevent the pistons 37 from falling at an uncontrolled rate when the pressure from them is removed.

A check valve V11 is provided in the circuit to the high load cylinders to operate as a pre-fill valve.

As described above, deflection of the path of the tube to be straightened is effected by operation of the cylinder 52 associated with the lower centre straightening roll 13, the upper centre straightening roll 12 moving in unison therewith. With reference to FIG. 5, this cylinder 52 is operated by the supply from pump P1 on the same supply circuit as the high load cylinders of the upper straightening rolls 10, 12, 14, to effect a deflection of the tube path which may be pre-set permanently, i.e. for a number of tubes, or which may be brought on temporarily, i.e. during the passage of each tube through the machine. Either of these operations may be performed automatically or manually by a second selector switch provided for this purpose. When this switch is in the manual position, the operator may still either select permanent deflection or temporary deflection by operation of the first selector switch. If this first selector switch is in the position for temporary deflection, the operator may apply the deflection by operation of a push-button but the button is so interlocked that the cylinder 52 cannot become operative until, as described above, the leading end of the tube being straightened has entered the last pair of straightening rolls '14, 15. The cylinder 52. will be returned to the down position before the machine can accept the next tube to be straightened.

As shown in FIG. 5 and as described above, pump P3 is operative to feed oil to both the cylinders 52, 66 of the lower centre straightening roll 13 and of the upper pinch roll 17 respectively. Suitable solenoid-operated direction valves V21 and V4 are provided for this purpose.

A further solenoid-operated direction valve V18 is provided to allow both pumps P1, P3 to supply oil at high pressure to the cylinder 52 of the lower centre straightening roll 13, which valve is situated at the junction of the feed lines to the cylinder 52 from the pumps P1, P3.

One important advantage of the hydraulically operated straightening machine described above is that means are provided for precluding oversize tubes from applying increased loads to the straightening rolls thereby risking damage to the tube or to the machine.

Another important advantage is that the deflection of the centre pair of straightening rolls may, as described above, be permanent for the duration of straightening a plurality of tubes or only temporary whereby the deflection is eifected and removed for each tube in turn. This latter feature of the invention is extremely important since it allows the deflection to be effected after the leading end of the tube has entered the machine and avoids the necessity of attempting to pass a tube with a bent leading end along a path that is not straight, i.e. a path in which the centre pair of rolls are offset from the two outer pairs of rolls.

It is to be appreciated that the machine is equally capable of straightening bars as well as tubes.

Also there may be provided more than three pairs of straightening rolls in which case two of the pairs of straightening rolls may be movable vertically, in unison,

in like manner to the centre pair of straightening rolls of the machine described above.

Furthermore the deflection could be set by lowering the centre pair of rolls instead of raising them.

I claim:

1. A straightening machine for bars or tubes comprising at least three pairs of driven straightening rolls arranged in line along the path of the bar or tube to be straightened, means for raising and lowering one of the rolls of each pair relatively to the other roll, means for raising and lowering the centre pair of rolls, in unison, into and out of the path of the bar or tube to be straightened to offset the centre pair of rolls from the outer pairs of rolls and means for arranging the rolls of each pair of rolls so that the bar or tube is rotated as it passes longitudinally therebetween, characterised in that one of the rolls of each pair is urged towards the other roll of the pair by a hydraulic jack, the hydraulic pressure of which jack is capable of being set by a pressure relief valve associated with the jack whereby any excess loading will cause the relief valve to lift and will hence prevent an increase of the predetermined hydraulic pressure on the bar or tube being straightened.

2. A machine as claimed in claim 1 in which the hydraulic jack associated with each of the outer pairs of rolls is capable of urging the upper roll of the respective pair of rolls towards the respective lower roll and hence into contact with the bar or tube being straightened.

3. A machine as claimed in claim 2 in which each hydraulic jack associated with the outer upper rolls is provided with a high load cylinder and a low load cylinder one of which may be selected for the application of hydraulic pressure on the bar or tube being straightened and both of which are provided with their separate pressure relief valves.

4. A machine as claimed in claim 1 in which for the centre pair of rolls there is provided a hydraulic jack for urging the upper roll towards the lower roll and hence into contact with the bar or tube being straightened and a second hydraulic jack for moving the lower roll vertically out of alignment with the lower rolls of the outer pairs of rolls, the centre lower roll being linked to its respective upper roll whereby the said second hydraulic jack moves the linked rolls in unison so that the gap therebetween is maintained constant.

5. A machine as claimed in claim 4 in which the jack associated with the upper centre roll is provided with a high load cylinder and a low load cylinder one of which may be selected for the application of hydraulic pressure on the bar or tube being straightened and both of which are provided with their separate pressure relief valves.

6. A machine as claimed in claim 1 in which the deflection of the path of the bar or tube being straightened, which is effected by offsetting the centre pair of rolls from the outer pairs of rolls, is applied prior to the passage of a bar or tube between the rolls.

7. A machine as claimed in claim 1 in which the deflection of the path of the bar or tube being straightened, which is effected by offsetting the centre pair of rolls from the outer pair of rolls, is applied during the passage of a bar or tube between the rolls and subsequently to the leading end of the bar or tube passing through the centre pair of rolls.

8. A machine as claimed in claim 7 in which the deflection is applied when the leading end of the bar or tube is passing between the outer pair of rolls which are located beyond the centre pair of rolls with respect to the direction of movement of the bar or tube.

9. A machine as claimed in claim 1 in which adjustable mechanical stops are provided for limiting the movement of each vertically movable roll towards its associated roll and in which the mechanical stop for each movable roll is provided by the means for raising and lowering the respective roll.

10. A machine as claimed in claim 1 in which there are a pair of driven pinch rolls for feeding a bar or tube into the straightening rolls, means for raising and lower ing one of the pinch rolls relatively to the other pinch roll and a hydraulic jack for urging the movable pinch roll towards the other pinch roll.

11. A machine as claimed in claim 10 in which means are provided for lifting the movable pinch roll on entry of the leading end of a bar or tube being straightened into the first pair of straightening rolls with respect to the direction of movement of the bar or tube.

References Cited UNITED STATES PATENTS MILTON S. MEHR, Primary Examiner U.S. Cl. X.R. 72162, 235, 246 

